Watercolor artists who take their craft seriously will know the different classification of the paints and how to exploit them. In my last tutorial I indicated the differences in the watercolor paper. Now we will analyze what goes on the paper and how these pigments behave for watercolor painting.

Classification of Pigments Used for Watercolor Painting

Pigments designated for watercolor painting are the same as in all mediums. Burnt sienna, for example, is ground from minerals. That same substance forms the volume in oil paints. If you don’t add white to burnt sienna oil paint and dilute it with a solvent, it’ll have the same transparent properties as watercolor. The difference between burnt sienna used in thicker mediums and that used in watercolor is the binder, not the raw pigments. Occasionally, my students have expressed they don’t paint with oils because they fear the paints are toxic or they have allergies and prefer to paint with watercolor. If you think you can get around this, I’m sorry to say that if you exclude petroleum-based solvents used with oils, you’re back in the same boat. So acrylics and water-mixable oil pigments are the same as watercolor in this sense. On a side note, I wish to dispel the rumor that oils are toxic in comparison with other paints. (You can visit your art manufacturer’s websites and read the labels for more information on this.)

In the thicker mediums we don’t have to worry that much about how pigments are classified but in watercolor it would be wise to understand them. When you compare a watercolor painting against any other medium you’ll notice that the painting seems to be more luminous and requires less light to stand out. It seems to me the entire painting is one value lighter. Why is this? A watercolor painting works somewhat like the plastic in movie reels. The very thin layer allows light to pass through and bounce off the white paper and more photons of light return to the eye, whereas as in the other mediums they bounce off. As soon as white is added to an oil or an acrylic painting it becomes opaque and blocks this phenomenon from occurring.

In broad terms pigments are classified as:

Transparent

Semi transparent

Opaque

Staining

Nonstaining

Permanence (the lifespan of a pigment before it fades)

Granular

Plus: Price range and quality (professional vs student)

Let’s start with the last two, professional vs student quality art materials. Professional-grade watercolor paints have pure pigment, meaning no artificial fillers fatten the tube to reduce the cost. I have a bone to pick with manufacturers when they call these “student quality” because sure enough my students, in order to reduce costs, will buy them. This will just make the whole painting process more difficult because you can get mud (when too many and/or low quality pigments are mixed and create a chemical reaction, dulling the color). It’s better to bite the bullet and buy the professional paints so you will encounter less hindrance. Unfortunately, art stores don’t spontaneously give recommendations. If I were an art store cashier I would say, “Take those back and buy the professional quality paints.” This applies to the other mediums as well.

If you shop for the most popular watercolor paints, Winsor and Newton, you’ll see the price range varies enormously. These are separated into Series1, 2, 3 and 4. They go from less expensive to expensive respectfully. The abundance or rarity of the raw materials is what determines the price. For example, ultramarine blue is mined from minerals so it’s quite abundant in nature. A 14 ml tube will cost about $12.50. Cobalt blue, which is close to ultramarine blue in color, will cost about $17.50.

Some watercolor artists want to stay uniquely within the transparent family. Personally, this isn’t a big issue for me. I select my paints on how close they are to nature, but I’m mostly a landscape artist. I prefer Indian red which is not as transparent and more muted than alizarin crimson, the latter being too intense and artificial looking for my landscape paintings. I still see a lot of luminosity in my watercolors because even if certain paints are more opaque they’re so diluted with water that you still get luminosity. Also the semi-opaque and opaque paints are less fugitive and are easier to control during wet-into-wet application because they’re heavier.

When it comes to glazing (putting a wash over a dry layer), however, I will only resort to using transparent paints. For example, if I feel my greens are too garish, I will glaze over them with burnt sienna instead of cadmium orange. On the other hand, a more opaque paint can help override an unpleasant area. If your rocks are too orange you can add cerulean blue. Naples yellow, being the most opaque of them, all can help indicate highlights on foliage. You can visit the manufacturers’ websites to see the classification of their products.

I always like to have an “undo button” for watercolor painting. If I’m not happy with an area I use a jet spray water bottle to remove unwanted paint. This is where it comes in handy to know the staining effects of pigments. Think of it as wine vs ketchup spilled on a fabric: It’s much harder to remove a wine stain. Hooker’s green and alizarin crimson are very staining and will stubbornly adhere to the paper. This is another why I threw alizarin crimson out of my palette and prefer Indian red. You can consult my personal palette on my website.

Now let’s talk about granular pigments. These are usually mined from minerals so no matter how much they become pulverized you still see mini deposits in the paper grooves. I find this effect to be distasteful when it comes to smooth water or blue skies, so I avoid ultramarine blue for these areas. Cobalt blue is a better alternative for blue skies, and Payne’s gray is generally a good choice for lakes. Both of them give a clean, smooth finishing. You have to experiment and see what works best for you.

In my next tutorial I’ll give some insight on how to control wet on wet applications and some valuable tips to make watercolor cooperate better.